A fuel guiderail assembly is a device that distributes fuel from a fuel guiderail to an injector, which in turn injects the fuel into the air inlet duct of an engine. An injector is controlled by the injection instruction signals sent by the engine's Electronic Control Unit (ECU). When an injector injects fuel, the amount of fuel and the pressure in the fuel guiderail drop, causing pressure fluctuations in the fuel guiderail. Pressure fluctuations cause the fuel guiderail to vibrate and generate noises and affect the injection results of the injector. For an injector to deliver good injection results, the pressure in the fuel guiderail must be kept stable. A damper is a device used to stabilize the pressure in a fuel guiderail. Depending on the installation position, dampers can be classified into external dampers and internal dampers. An external damper is installed outside a fuel guiderail, and an internal damper is installed inside a fuel guiderail. The internal damper must be securely held in place inside the fuel guiderail, or else the damping effects of the damper are affected and noises are often generated when the engine is working.